The present application relates to brake-by-wire brake systems and, more particularly, to extreme emergency braking systems for brake-by-wire brake systems.
Government regulations often require vehicles employing conventional hydraulic brake systems to include at least two independent brake commands: a nominal brake command and a park brake command. The nominal brake command typically is associated with the normal pedal-based brake function or other traditional downgrade modes. The park brake command typically is associated with a hand brake lever or the like for providing continuous braking when the vehicle is parked and, in the event of a severe fault with the nominal brake command, may be employed to provided extreme emergency braking when the vehicle is in motion.
Brake-by-wire brake systems have been developed to replace traditional hydraulic brake systems with brake systems employing an electrical connection, rather than the traditional hydraulic connection, between the user's brake input and the brake unit. Brake-by-wire brake systems have been employed in both nominal brake command systems and park brake command systems.
Brake-by-wire brake systems typically employ numerous redundant systems and components to ensure proper operation in response to a nominal brake command in the event of an electrical failure in the system. Nonetheless, there remains a possibility that the nominal system may fail.
Accordingly, there is a need for a brake-by-wire brake system having a nominal brake command system independent of the park brake command system such that the park brake command system may be used for extreme emergency braking.